In addition to the alphabet soup of certifications I have (MCSE: Security, CCNA, MCITP: Database Administrator, etc.), how to I correctly identify or designate my ITIL certification on resumes, sig files, and the like?

I've yet to find an authoritative answer, and all of the other certs I have list specific requirements for how to use the certification designators.

The only certification I've ever used a designation on is the PMP. I only have used that when I am in the role as a Project Manager. I don't use it as a 'hey look what I have!' title but more as a 'Feel free to use PMBOK terminology with me and I will understand it'. Back when I held my MCSE, CCNA and CCNP I never put that on an email signature. I don't even do it with my MBA which trumps about ever thing I've held.

For the ITIL foundation which I take in about 2 weeks I only plan on throwing it on my resume and informing my current company that I knocked it out for them.